The inventors are not aware of the existence, in this field, of certification criteria established in connection with means of the kind mentioned used during the manufacture and repair of parts and structures produced with composite materials nor, obviously, of the availability of technology associated with the inspection means necessary for performing the thermal certification of said means.
It is only known of the existence of one standard for the certification of the said heater blankets used for repair of parts and structures of the abovementioned type, although the technology which is used for said certification is measurement by means of optical radiation pyrometry.
The known certification systems of the abovementioned type, based on measurements performed using optical radiation pyrometers, are based on the manual and pointwise recording of the instantaneous temperature value, indicated by a point having a predefined diameter (target size) at a focal distance which is also defined.
The measurements are performed manually, repeating them, normally up to ten times, at each one of the points which define a grid traced on the surface of the blanket to be certified. These values thus acquired are further processed, performing the appropriate calculations so as to obtain the statistical parameters (mean values, standard deviation, variance) as well as evaluation of the “measurement uncertainty factor” associated with the values obtained.
Once said values have been determined and compared with the tolerances defined in the certification requirements, a decision is taken as to the conformity or non-conformity of the heater blanket which is undergoing certification.
This pyrometric certification method according to the prior art is applied in accordance with the definitions of the internal standard for certification of heater blankets and basically consists of the following steps:                definition and manual tracing of a grid suited to the dimensions of the blanket to be certified, so as to thus define the minimum number of points to be evaluated;        preparation of the test configuration, application of a vacuum and maintaining the vacuum for the duration of the test;        heating of the blanket to the nominal temperature, typically in the region of 185° C. and maintaining this stabilized condition for a duration of between about 15 and about 35 minutes or for the time necessary to allow recording of the necessary data (temperature values);        pointwise measurement, by means of an optical radiation pyrometer calibrated within a temperature range which includes the nominal temperature value, of the temperatures on the surface of the heater blanket which, during use, is intended to come into contact with the surface of the composite material part to be treated;        repetition, a sufficient number of times, of the measurements taken at all the points (typically 10 repetitions per point), with the aim of obtaining a representative range of values which allows the appropriate statistical calculations;        cooling and interruption of the vacuum;        determining the values of the corrected readings, on the basis of the data in the pyrometer calibration certificate; and        performing the statistical calculations necessary for determining whether, with the values obtained, it is possible to guarantee the uniformity tolerance required by the applicable standard.        
This pyrometric method has the following problems and limitations:
a) very high measurement uncertainty: the value of this parameter is practically of the same order of magnitude as the temperature uniformity tolerance required of heater blankets. The reasons for these values lie in the poor precision of the method and the fact that it consists of a “manual” method which is affected by many influencing factors which result in a high variability of the readings obtained;
b) low reliability of the values obtained;
c) extreme slowness in the acquisition of the values, which results in a major increase in the cost of certification, so that it is not cost-effective from an industrial point of view; and
d) impossibility of obtaining any type of graphical record: the temperature values are acquired manually by the technician performing the tests.